plexus

plexus

[plek´sus] (pl. plex´us, plexuses) (L.)

a network or tangle, chiefly of veins or nerves; see also rete. adj., adj plex´al.

plexus basila´ris a venous plexus of the dura mater located over the basilar part of the occipital bone and the posterior part of the body of the sphenoid bone, extending from the cavernous sinus to the foramen magnum.

cardiac plexus the plexus around the base of the heart, chiefly in the epicardium, formed by cardiac branches from the vagus nerves and the sympathetic trunks and ganglia, and made up of sympathetic, parasympathetic, and visceral afferent fibers that innervate the heart.

cervical plexus a nerve plexus formed by the ventral branches of the first four cervical spinal nerves and supplying the structures in the region of the neck. One important branch is the phrenic nerve, which supplies the diaphragm.

choroid plexus infoldings of blood vessels of the pia mater covered by a thin coat of ependymal cells that form tufted projections into the third, fourth, and lateral ventricles of the brain; they secrete the cerebrospinal fluid.

coccygeal plexus a nerve plexus formed by the ventral branches of the coccygeal and fifth sacral nerve and by a communication from the fourth sacral nerve, giving off the anococcygeal nerves.

cystic plexus a nerve plexus near the gallbladder.

dental plexus either of two plexuses (inferior and superior) of nerve fibers, one from the inferior alveolar nerve, situated around the roots of the lower teeth, and the other from the superior alveolar nerve, situated around the roots of the upper teeth.

lumbar plexus one formed by the ventral branches of the second to fifth lumbar nerves in the psoas major muscle (the branches of the first lumbar nerve often are included).

lumbosacral plexus the lumbar and sacral plexuses considered together, because of their continuous nature.

lymphatic plexus an interconnecting network of lymph vessels that provides drainage of lymph in a one-way flow. An example is the lymphocapillary vessels, collecting vessels, and trunks.

myenteric plexus a nerve plexus situated in the muscular layers of the intestines.

nerve plexus a plexus composed of intermingled nerve fibers.

pampiniform plexus

1. in the male, a plexus of veins from the testis and the epididymis, constituting part of the spermatic cord.

2. in the female, a plexus of ovarian veins draining the ovary.

sacral plexus a plexus arising from the ventral branches of the last two lumbar and first four sacral spinal nerves.

plexus

aortic plexus, abdominal one composed of fibers that arise from the celiac and superior mesenteric plexuses and descend along the aorta. Receiving branches from the lumbar splanchnic nerves, it becomes the superior hypogastric plexus below the bifurcation of the aorta. Branches are distributed along the adjacent branches of the aorta.

aortic plexus, thoracic one around the thoracic aorta formed by filaments from the sympathetic trunks and vagus nerves, and from which fine twigs accompany branches of the aorta; continuous below with the celiac plexus and the abdominal aortic plexus.

autonomic plexus any of the extensive networks of nerve fibers and cell bodies associated with the autonomic nervous system; found particularly in the thorax, abdomen, and pelvis, and containing sympathetic, parasympathetic, and visceral afferent fibers.

Batson's plexus the vertebral plexus (1) considered as a whole system.

brachial plexus a nerve plexus originating from the anterior branches of the last four cervical and the first thoracic spinal nerves, giving off many of the principal nerves of the shoulder, chest, and arms.

Brachial plexus. Anterior view, showing the most major branches.

cardiac plexus the plexus around the base of the heart, chiefly in the epicardium, formed by cardiac branches from the vagus nerves and the sympathetic trunks and ganglia.

carotid plexus any of three nerve plexuses surrounding the common, external, and internal carotid arteries, particularly the last.

cavernous plexus a plexus of sympathetic nerve fibers related to the cavernous sinus of the dura mater.

celiac plexus

1. a network of ganglia and nerves lying in front of the aorta behind the stomach, supplying the abdominal viscera.

2. a network of lymphatic vessels, the superior mesenteric lymph nodes, and the celiac lymph nodes.

cervical plexus a nerve plexus formed by the anterior branches of the first four cervical nerves, supplying structures in the neck region.

choroid plexuses infoldings of blood vessels of the pia mater covered by a thin coat of ependymal cells that form tufted projections into the third, fourth, and lateral ventricles of the brain; they secrete the cerebrospinal fluid.

coccygeal plexus a nerve plexus formed by the anterior branches of the coccygeal and fifth sacral nerves and by a communication from the fourth sacral nerve, giving off the anococcygeal nerve.

cystic plexus a nerve plexus near the gallbladder.

dental plexus either of two plexuses (inferior and superior) of nerve fibers, one from the inferior alveolar nerve situated around the roots of the lower teeth, and the other from the superior alveolar nerve situated around the roots of the upper teeth.

enteric plexus a plexus of autonomic nerve fibers within the wall of the digestive tube, made up of the submucosal, myenteric, and subserosal plexuses.

esophageal plexus a plexus surrounding the esophagus, formed by branches of the left and right vagi and sympathetic trunks and containing also visceral afferent fibers from the esophagus.

Exner's plexus superficial tangential fibers in the molecular layer of the cerebral cortex.

gastric plexuses subdivisions of the celiac portions of the prevertebral plexuses, accompanying the gastric arteries and branches and supplying nerve fibers to the stomach.

Heller's plexus an arterial network in the submucosa of the intestine.

hypogastric plexus, inferior the plexus formed on each side anterior to the lower part of the sacrum, formed by the junction of the hypogastric and pelvic splanchnic nerves; branches are given off to the pelvic organs.

hypogastric plexus, superior the downward continuation of the abdominal aortic plexus; it lies in front of the upper part of the sacrum, just below the bifurcation of the aorta, receives fibers from the lower lumbar splanchnic nerves, and divides into right and left hypogastric nerves.

lumbar plexus

1. one formed by the anterior branches of the second to fifth lumbar nerves in the psoas major muscle (the branches of the first lumbar nerve often are included).

2. a lymphatic plexus in the lumbar region.

Lumbar plexus, in yellow, in anterior (A) and lateral (B) views, with the divisions forming the lumbosacral trunk shown in white, as is the sacral plexus.

lumbosacral plexus the lumbar and sacral plexuses considered together, because of their continuous nature.

1. a venous plexus posterolateral to the pharynx, formed by the pharyngeal veins, communicating with the pterygoid venous plexus, and draining into the internal jugular vein.

2. one formed chiefly by fibers from branches of the vagus nerves, but also by fibers from the glossopharyngeal nerves and sympathetic trunks, and supplying most of the muscles and mucosa of the pharynx and soft palate.

phrenic plexus a nerve plexus accompanying the inferior phrenic artery to the diaphragm and adrenal glands.

1. a subdivision of the inferior hypogastric plexus that supplies nerve fibers to the prostate and adjacent organs.

2. a venous plexus around the prostate gland, receiving the deep dorsal vein of the penis and draining through the vesical plexus and the prostatic veins.

pterygoid plexus a network of veins corresponding to the second and third parts of the maxillary artery; situated on the medial and lateral pterygoid muscles and draining into the facial vein.

pulmonary plexus one formed by several strong trunks of the vagus nerve that are joined at the root of the lung by branches from the sympathetic trunk and cardiac plexus; it is often divided into anterior and posterior parts.

rectal plexus

1. a venous plexus that surrounds the lower part of the rectum and drains into the rectal veins.

plex·us

A network or interjoining of nerves and blood vessels or of lymphatic vessels.

[L. a braid]

plexus

Any interlacing network, as of nerves, blood or lymph vessels. The solar plexus is a network of AUTONOMIC nerve fibres lying on the abdominal AORTA.

plexus

a network of interlaced blood vessels or nerves.

plexus

A network of interweaving nerves, blood vessels or lymphatic vessels.cavernous plexus A network of nerve fibres derived from the internal carotid nerve and located on the inferomedial aspect of the internal carotid artery in the cavernous sinus. It supplies sympathetic innervation via the ciliary and gasserian ganglia to almost all of the orbit, including fibres to the dilator pupillae muscle, Müller's superior palpebral muscle, the ciliary muscle and vasoconstrictor fibres for the blood vessels of the eye. SeeHorner's syndrome.ciliary venous plexus A network of vessels situated in the outer portion of the ciliary body. It receives blood from the ciliary muscle and drains into anterior ciliary vein. It also communicates with the intrascleral venous plexus. Syn. ciliary plexus.deep episcleral plexusSeepericorneal plexus.episcleral venous plexus A network of vessels near the limbus which receives blood from the intrascleral plexus and canal of Schlemm via collector channels and drains into the anterior ciliary veins. It also receives blood from the conjunctival veins and drains the perilimbal conjunctiva.internal carotid plexus A network of nerve fibres derived from the internal carotid nerve and located on the lateral side of the internal carotid artery near the apex of the petrous bone. It sends sympathetic axons to the abducens, ophthalmic and nasociliary nerves, the deep petrosal nerve, the caroticotympanic nerve and the ophthalmic and lacrimal arteries. Seesuperior cervical ganglion.intrascleral venous plexus A network of vessels situated in the deep layers of the sclera near the limbus. It is made up of the deep and mid scleral plexuses. It receives aqueous humour from the canal of Schlemm via collector channels, as well as blood from the ciliary venous plexus. It drains into the anterior ciliary veins.pericorneal plexus A network of vessels situated around the limbus and formed by the anastomosing of the episcleral arteries (branches of the anterior ciliary arteries) and the conjunctival arteries. It forms a series of arcades parallel to the corneal margin. This plexus is arranged in two layers: (1) a superficial conjunctival pericorneal plexus liable to injection in inflammation of the superficial cornea or conjunctiva (conjunctival injection) (2) a deep episcleral plexus liable to injection in diseases of the iris, ciliary body or deep portion of the cornea, or angle-closure glaucoma (ciliary injection). Seeciliary arteries; anterior ciliary vein.

plex·us

, pl. plexus (plek'sŭs) [TA]

A network or interjoining of nerves and blood vessels or of lymphatic vessels.

[L. a braid]

plexus (plek´sus),

n a network or tangle, especially of nerves, lymphatics, or veins.

plexus, Haller's,

n.pr a nerve plexus of sympathetic filaments and branches of the external laryngeal nerve on the surface of the inferior constrictor muscle of the larynx.

plexus, intermediate,

n a middle zone of the periodontal ligament situated between the cemental group of fibers attached to the root of the tooth and the alveolar group of fibers attached to the alveolar bone (Sharpey's fibers). The three groups of fibers are woven together by small, thick strands of collagen fibers. The interweaving of fiber bundles of the intermediate plexus allows for tooth eruption and tooth movement between the cemental and alveolar periodontal fibers.

plexus

pl. plexus, plexuses [L.] a network or tangle, chiefly of veins or nerves.

the plexus around the base of the heart, chiefly in the epicardium, formed by cardiac branches from the vagus nerves and the sympathetic trunks and ganglia, and made up of sympathetic, parasympathetic and visceral afferent fibers that innervate the heart.

a plexus of autonomic fibers and sympathetic nerve ganglia which surround the origin of the celiac artery, and supply the abdominal viscera.

celiacomesenteric plexus

a plexus of autonomic nerve fibers and sympathetic ganglia around the origin of the celiac and cranial mesenteric arteries; called also solar plexus.

cervical plexus

a network of nerve fibers formed by the first four cervical nerves and supplying the structures in the region of the neck.

choroid plexus

infoldings of blood vessels of the pia mater covered by a thin coat of ependymal cells that form tufted projections into the third, fourth, and lateral ventricles of the brain; they secrete the cerebrospinal fluid.

coccygeal plexus

a nerve plexus formed by the ventral branches of the coccygeal and last sacral nerves.

either of two plexuses (inferior and superior) of nerve fibers, one from the inferior alveolar nerve, situated around the roots of the lower teeth, and the other from the superior alveolar nerve, situated around the roots of the upper teeth.

gonadal plexus

the collection of parasympathetic and sympathetic nerves to the gonads.

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